Portable fire alarm device



Dec. 14, 1948. R. E. YOUNG 2,456,038

PORTABLE FIRE ALARM DEVICE lFiled May 29, 1947 Patented Dec. 14, 1948UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to improvements in alarm signal devices and moreparticularly to an improved unitary. electrically operated fire alarmsignal device adapted to be plugged into an electrical convenienceoutlet and supported thereby to give an audible alarm ii subjected to atemperature indicating the presence of fire in the space contiguousthereto.

It is among the objects oi. the invention to provide an improved,electrically operated, portable signal device which may be plugged intoa conventional electrical convenience outlet to be bodily supported bythe outlet or which may be supported at some location remote from anoutlet and electrically-connected thereto by a suitable extension cord,which will give a loud, clear, continuous and distinctive audible signalwhen the temperature in the space contiguous thereto exceeds apredetermined value, which is simple in construction and includes aminimum number of simple parts most of which are of conventional designreadily available on the market, which is neat and attractive inappearance and may be installed without any changes in or additions tothe wiring of the building or other structure in which it is used.

Other objects and advantages will become apparent from a considerationof the following description in conjunction with the accompanyingdrawing wherein:

Figure l is a longitudinal cross-section of an alarm signal deviceillustrative of the invention taken substantially on the lines i-i ofFigure 2.

Figure 2 is a transverse cross-section taken substantially on the line2-2 of Figure 1.

Figure 3 is a fragmentary cross-section taken substantially on the line3-4 of Figure 2, and including an end elevation of a thermostatic switchconstituting an operative component of the device. 7

Figure 4 is a fragmentary cross-section taken substantially on the line4-4 of Figure 2 including a top plan view of the thermostatic switchshown in Figure 3.

Figure 5 is a fragmentary cross-section on the line H of Figure 1showing an end elevation of an electro-magnetic vibrator constituting anoperative component of the device.

Figure 6 is a diagrammatic wiring diagram of the electrical componentsof the device.

Figure 7 is a rear elevation of a fragmentary portion of the deviceshowing the adjustment of the thermostatic switch shown in Figures 3 and4.

With continued reference to the drawings the device has an enclosingcasing comprising a hol- 2 low ventilated front cover member l0detachably secured to a flat backing plate ll preferably formed ofinsulating material. The backing plate may be centrally provided on itsrear back side with a re-inforcing plate l2 providing a second plateportion through which extends a pair of prongs or fingers l3 adapted tobe received in a conventional electrical convenience outlet toelectrically energize the alarm device and simultaneously support thedevice from the convenience outlet.

A transformer generally indicated at It is secured to the casing and hasone side of its primary winding l5 electrically connected by a conductorIt with one of the fingers It. The other finger i3 is electricallyconnected by a conductor I! with one contact l8 of a thermostatic switchgenerally indicated at it, the other contact 20 of which is connected bya conductor 2i with the opposite side of the transformer primary windingl5.

In the thermostatic switch illustrated the contact i8 is a fixed contactsupported on the backing plate ii and the contact 20 is a movablecontact carried at the outer end of a coiled bi-metallic strip 22 theopposite end of which is secured to a rotatable pin 23 Journaled in abushing provided in the backing plate i I and having at the outside ofthe backing plate a head provided with a transverse slot 24 by means ofwhich the pin may be rotated to adjust the switch. A dial 2! is mountedon the outside of the backing plate surrounding the pin 23 and isproperly indexed to indicate the setting of the thermostatic switch. Apointer 20 may be attached to the pin and movable over the dial indiciato accurately indicate the switch setting.

With the arrangement above described, when the bi-metallic element 22brings the contact 20 against the fixed contact ill the circuitincluding the primary winding I! of the transformer ll will be closed.

A pair of parallel solenoid coils 21 are secured to the casing and avibrator bar-28 extends across the outer ends of these coils. One end oithe bar 28 is rigidly connected to the corresponding end of a leafspring 29 the opposite end of which is secured to a fixed bracket 30. Amovable contact 3| is carried by the bar 28 opposite a fixed contactmember 32" which provides a limit stop for movement of the bar away fromthe adjacent end of the coils 21. An electrical conductor 33 connectsthe fixed contact 32 with one side of the secondary winding of thetransformer i4 and a conductor connects one side of the coils 21 mucosaductor It connects the opposite side of the coils with the opposite sideof the secondary winding. Thus, when the circuit including the primarywinding ll of the transformer is closed the secondary winding will beenergized and when the contacts Ii and 82 are together current will flow4 is quickly and positively responsive to any temperature rise above thetemperature value tor which it is set.

' The invention 'may be embodied in other specinc, terms withoutdeparting from the spirit or essential characteristics thereof. Thepresthrough the secondary winding and throughthe coil. 21 energizing thecells to attract the bar It thereby separating the contact 8! from thecontact 02 and interrupting the coil energizing circuit. This causes thebar 20 to vibrate in the conventional manner of bumers, bell ringers.and similar devices. 7

Bar 10 is resiliently urged away from the coils 21 by a compressionspring interposed between the outer end of the bar and a fixed bracketor abutment 38, the strength oi. spring 31 being suiiicient to quicklymove the bar away from the coils but insumcient to prevent movement ofthe bar by the magnetic attraction of the coils when energized. Thisspring has the effect of increasing the rapidity of vibration oi the bar20 and thereby raising the pitch oi the audible signal produced by thedevice. A flat plate 8. is secured to the bar II and projectslaterallytherefrom to magnify the sound effect produced by vibration or the bar.

While the device is particularly useful as a portable ilre alarm. itmaybe given a sumciently wide range of adjustment, as for example, therange included between 70 and 220 Fahrenheit as indicated in Figure 7,which would render it'usei'ul for various other purposes. For example,the device might be placed in a broader house to give an alarm if thetemperature within the house reached a value dangerous to the health 0!chicks housed therein or could be used in a green-hoube, tobacco curingbar, or any other structure or building in which it is necessary ordesirable to keep the temperature below a predetermined maximum value..Y r

The device is light in weight, neatsndattractive .in appearance, andcompletely portable -so that it may be quickly and easily installed inany out embodiments are. therefore. to be considered in all respects asillustrative and not restrictive, the scope oi the invention beingindicated by the appended claim rather than by the ioregoingdescription, and all changes which come within the meaning and range ofequivalency of the claim are, therefore, intended to be embracedtherein.

What is claimed:

A portable. unitary alarm device for indicating a temperature above apredetermined value in the space contiguous thereto comprising a casinghaving a back plate and a front cover detachablv secured to said backplate. a pair of fingers projecting from the back side of said plate forreception in an electrical convenience outlet to 4 support andelectrically energize said device, a

location in which there is a conventional electrical convenience outletplug. It requires nochanges in or additions to the ordlnaryhouse wiringand transformer mounted at the front side of said plate, an electricalconnection between one oi said fingers and one side 01' the primarywinding of said transformer, an adjustable thermostatic switch mountedon theiront side oi said plate. an electrical connection between onecontact of said switch and the other side of said primary winding, anelectrical connection between the other contact 01" said switch and theother of said fingers. an electro-maanetic vibrator mounted at the frontside 01' said plate, and electrical connections between said vibratorand the opposite sides of the secondary winding of said transformer tooperate said vibrator upon closing of said thermostatic switch.

RICHARD a. YOUNG.

REFEREivcEs crrrm The following references are of record in the file ofthis patent:

UNITEDSTATES PATENTS

